When acid is added to a metal carbonate, the evolved gas turns lime water milky. What is the correct identification and reason?
Answer and explanation
Correct answer: Carbon dioxide because it forms calcium carbonate
Metal carbonates react with acids to produce a salt, water, and carbon dioxide: carbonate + acid → salt + H₂O + CO₂. When the gas is passed through limewater, Ca(OH)₂, it reacts to form insoluble calcium carbonate, CaCO₃, which appears milky: CO₂ + Ca(OH)₂ → CaCO₃ + H₂O. Therefore option A gives both the correct gas and the correct reason.
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What is the correct answer to this question?
Carbon dioxide because it forms calcium carbonate
Why is this the correct answer?
Metal carbonates react with acids to produce a salt, water, and carbon dioxide: carbonate + acid → salt + H₂O + CO₂. When the gas is passed through limewater, Ca(OH)₂, it reacts to form insoluble calcium carbonate, CaCO₃, which appears milky: CO₂ + Ca(OH)₂ → CaCO₃ + H₂O. Therefore option A gives both the correct gas and the correct reason.
Which subject and chapter does this question cover?
This is a Class 10 Science question. Chapter: Chemical Substances – Nature and Behaviour. Topic: Acids, Bases, and Salts.
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